Facsimile recording drum electrode

ABSTRACT

A partially folded strip electrode of electrically conducting sheet material is held curved around a drum by a coiled spring, elastic strand or spring tensioned wire attached to the drum whose intermediate portion overlies and yieldingly holds the strip against the drum with one fold extending flexibly away from the drum for cooperating with a blade electrode in marking an intermediate strip of electrical recording paper.

United States Patent 1 91 Simpkins et al.

[ 1 May 29,1973

FACSIMILE RECORDING DRUM ELECTRODE Inventors: Frederick W. Simpkins,Hudson; Er-

, nest Bliudnikas, Brockton, both of Mass.

Assignee: Alden Research Foundation, Westboro, Mass.

Filed: Nov. 22, 1971 Appl. No.: 200,678

Related (1.8. Application Data Continuation-impart of Ser. No. 130,111,April 1, 1971, abandoned.

Us. 01. ..346 139 0, 346/101 rm. (:1. ..G0ld 15/06 Field of Search..346/101, 139 c, 139 R,

346/74 E, 74 CH; 178/6.6 R

[56] References Cited UNITED STATES PATENTS 2,568,754 9/1951 Lupish..346/10l 2,580,464 l/l952 Rohrberg .....346/l0l.

2,591,640 4/1952 Ti'ibble ..346/l0l 2,597,199 5/1952 Stamper et al.....346/1 14 X 7 2,962,340 11/1960 Alden ..346/10l 3,491,365 1/1970Desautels 3,577,150 5/1971 Alden ..346/l0l X Primary Examiner-J0seph W.Hartary Attorney-James H. Grover [57] ABSTRACT A partially folded stripelectrode of electrically conducting sheet material is held curvedaround a drum by a coiled spring, elastic strand or spring tensionedwire attached to the drum whose intermediate portion overlies andyieldingly holds the strip against the drum with one fold extendingflexibly away from the drum for cooperating with a blade electrode inmarking an intermediate strip of electrical recording paper.

30 Claims, 17 Drawing Figures SIG.

Patented May 29, 1973 2 Sheets-Sheet 1 INVENTORS FREDERICK w. SIMPKINSERNEST BLIUDNIKAS ATTORNEY Patented May 29, 1973 3,736,594

2 Sheets-Sheet 2 INVENTORS FREDERICK W. SIMPKIN ER NE ST BLIUDNIKAS FIG.I? W Maw ATTORNEY FACSIMILE RECORDING DRUM ELECTRODE This application isa continuation-in-part of application Ser. No. 130,111 for FacsimileRecording Drum Electrode, filed Apr. 1, 1971, now abandoned. Referenceis also made to U.S. Pat. application Ser. No. 793,132 for RecordingHelix, filed Jan. 22, 1969 by Milton Alden, now U.S. Pat. No. 3,577,150.

BACKGROUND OF THE INVENTION In the above referenced application there isdisclosed an elongate recording electrode adapted to be helicallywrapped around and secured to a rotating facsimile recording drum. Theelectrode consists of an elongate metal strip folded longitudinally toform two angularly disposed lengthwise panels the first of which issecured in a helical groove around the drum. The strip is transverselyserrated to permit torsional twisting into helical shape with the secondpanel standing outwardly of the drum to form an outer, helical recordingedge. In operation the drum is rotated opposite a linear, blade-likeelectrode with a moving sheet of electrolytic or other electrosensitivepaper between the electrodes. As is well known in the facsimile art,rotation of the drum while facsimile signals are applied to the twoelectrodes causes the paper to be marked as the pressure point of thehelical electrode against the linear electrode travels across the paper.In such operation the folded, serrated helical electrode of theapplication referred to flexes at its outer recording edge and maintainsgood recording contact with the paper without applying undue wearingpressure on the paper.

The object of the present invention is to provide an improved way ofsecuring the folded helical or other curved electrode to the rotatingdrum or like cylindrical support, which is quick and simple, whichprovides a more resilient recording edge, and which increases theservice life of the electrode.

SUMMARY OF THE INVENTION According to the invention a facsimilerecording scanning assembly comprises a cylindrical support, an elongatestrip electrode curved around the support, an elongate holddownextending substantially the length of the strip and yieldingly bearingon the strip to urge the strip toward the support, and means forattaching the strip and holddown to the support. Preferably the supportis a drum with a helical groove receiving the strip electrode and thehelical electrode is a serrated strip folded to form two lengthwisepanels which are allowed to rock in the groove by the holddown.Alternatively a longitudinally grooved ribbon may be secured helicallyon an ungrooved drum. The holddown may be a single, helical spring orother strand-like elastomer, or a relatively non-distensiblewireprovided with a tension spring at one or both ends. A nonyieldingconnection may be made between one end of the strip electrode and thedrum or other cylindrical support to prevent the electrode from slippingalong the groove in the drum.

DRAWINGS For the purpose of illustration typical embodiments of theinvention are shown in the accompanying drawing in which:

FIG. 1 is a front elevation of a strip electrode on a facsimile recorderdrum showing other parts of the recorder schematically;

FIG. 2 is an isometric view of the strip electrode of FIG. 1;

FIG. 3 is a section on line 33 of FIG. 1; FIG. 4 is an enlarged fragmentof the drum;

FIG. 5 is a section like FIG. 3 showing a modified drum;

FIGS. 6 and 7 are alternate forms of strip electrode holddown;

FIG. 8 is a section on line 8-8 of FIG. 4;

FIGS. 9 and 10 are sections like FIG. 3 showing alternate forms of drumand strip electrode;

FIG. 11 is a fragmentary elevation of a further modified form of thedrum of FIG. 1;

FIG. 12 is a plan view of an insert band for attachment to the drum ofFIG. 11;

FIG. 13 is a plan view of a further form of strip electrode forattachment to the drum of FIG. 11;

FIG. 14 is an enlarged section on line l414 of FIG. 12',

FIG. 15 is an enlarged section on line l5l5 of FIG. 13;

FIG. 16 is an isometric view of a foam rubber strip used with the drumof FIG. 11; and

FIG. 17 is a section like FIGS. 14, of an assembly of the parts of FIGS.11 to 16.

DESCRIPTION Shown schematically in FIG. 1 is a generally well knownelectrolytic recorder comprising a cover 1 hinged to a base 2. The cover1 mounts a linear blade 3 forming one electrode. Journalled in the baseis a cylindrical drum 4 of insulating material rotated during operationby a motor M. Helically curved around the drum is a second electrode 6whose outer edge presses through a sheet of recording paper against theblade electrode 3 at a spot which travels from left to right as the drumis rotated in the direction of the arrow 4. The sheet of electrolyticpaper (not shown) is fed from a supply through a recording plane Pbetween the blade 3 and helical electrode 6 approximately at the hingeline of the cover and base. Facsimile signals are impressed on theelectrode from a source 7 through electrical connections 8 to the blade3 and the hub 5 of the drum 4. The signals electrically mark the paperas the pressure spot between the helical electrode and blade electrodetraverses the paper. During recording it is essential for uniformmarking of the paper that a uniform but light and yielding pressure bemaintained on the paper by flexing the helical electrode. This pressuremay result in abrasion and wearing of the helical electrode and ultimateexhaustion or fracture of the electrode, limiting its life, particularlyin high speed operation.

A preferred form of helical electrode 6 shown in detail in FIGS. 2 to 4is formed of an elongate flexible strip or sheet of 0.003 to 0.005 inchthick stainless steel No. 302, half hard, or beryllium copper No. 25,half hard. The strip is partially folded lengthwise along a line 9 toform two longitudinal panels lland 12 at about Notches 13 are cut whollythrough the base panel 12 and part way through the upstanding panel 11leaving a more lightly flexible bridge 14 below the recording edge 16 ofthe electrode. Intermediate the notches, tabs 17 are cut from the upperpanel 11 and left in the same plane as the base panel 12, during foldingof the upstanding panel. According to the previously mentionedapplication Ser. No. 793,132 the tabs l7 and base panel 12 were securedon the drum by overlying strips adhered to the tabs, base panel and drumcontinuously along the base of the electrode 6 allowing only the upperpanel ll to flex and restricting the flexing to a short length of theupper panel near the pressure spot.

In FIG. 1 to 4 of the present application the helical strip electrode 6is shown secured to the drum 4 by a coiled tension holddown spring 18.For an I 1 inch length drum the holddown spring is approximately 12inches long, formed of 0.020 inch steel spring wire coiled to an outerdiameter of one-eighth inch. Generally the spring holddown isapproximately the length of the drum and is stretched on attachment tothe drum. Eyelets 19 formed at each end of the holddown spring arehooked over a screw head 20 at each end 'of the drum (FIGS. 4 and 8).The screw head 20 is eccentrically disposed off the axis of its shank 21which is threaded radially into the drum 4. To attach the spring eyeletsthe screw heads are turned 180 from the position shown in FIG. 4, andafter the eyelet is hooked the screw heads are returned to the positionshown applying added tension to the spring and locking the eyelets underthe eccentric head. As shown in FIG. 1 an electrical connection 10 ismade inside the drum between the screw head and its axle 5, to completethe circuit between the facsimile signal source 7 and the helicalelectrode 6.

The drum is provided with a helical groove 22 of rectangular crosssection which receives the base panel 12 and tab 17 of the electrodestrip 6, the edges of the groove inhibiting lateral shift of the strip.The electrode strip is held in the groove only by the spring holddown,and to prevent shifting of the electrode along the groove a short lengthof wire 23 is hooked in a notch of the strip and twisted around theeccentric screw head 20. Oddly, the trailing end of the electrode stripmust be anchored, that is, the right hand end in FIG. 1, the end last tooppose the blade 3 in each scanning revolution.

With the spring holddown 18 of FIGS. 1 to 4 the electrode strip 6 isheld accurately in helical form and applies adequate yielding pressureon the recording paper during operation. The holddown spring seats atthe fold of the strip and allows the strip to rock generally about thefold line 9, with both the tab 17 and the base panel 12 flexing. Inaddition to this lateral rocking the spring holddown allows alongitudinal rocking or flexing of the segments of the strip between thebridges 14 at the ends of the notches 13. Flexure is thus distributedover a considerable length of the strips and involves all parts of thestrip in a wave moving along the strip so that stress is not placed on alocalized portion of the edge 16 opposite the blade electrode andlocalized metal fatigue is avoided. Additionally, longitudinaldistension of the coiled spring holddown occurring during flexure of thestrip results in rubbing of the holddown on the strip and maintenance ofa good electrical contact between a considerable length of the holddownand strip.

Consequently the occurrence of localfractures is greatly reduced. Thelife of the helical electrode has been extended as much as ten times thenormal expectancy at the high speed of 1,800 rpm. The spring holddownallows the electrode strip to seat in and conform to the drum grooveduring testing or the first few hours of operation, resulting in veryuniform pressure across the recording paper. Installation or replacementof the strip electrode or the holddown spring is extremely rapid andeasy.

The same advantages are present in a modified structure shown in FIG. 5wherein a V-shaped groove 22a is cut helically in a drum 4a. Anelectrode strip 16a has base segments 12a, notches 13a and bridges 14a,like the strip 6 of FIGS. 1 to 4, but lacks the tabs 17. The sameholddown spring 18 secures the strip in the groove 22a while allowingall portions of the strip to rock and flex laterally and longitudinally.With either form of strip electrode the spring holddown 1, coiledthroughout most of its length may be replaced by the holddown shown inFIG. 6 which comprises a coiled spring at one end and a straight lengthof the spring wire throughout the length which will overlie theelectrode strip. Alternatively, as shown in FIG. 7, the entire length ofthe holddown may consist of a strand 18b of conducting or non-conductingmaterial such as rubber or any other elastomer. With a non-conductingholddown the anchoring wire 23 of FIG. 4 electrically connects theelectrode strip 18 to 18a to the anchoring screw 21.

FIG. 6 also illustrates a modified wire end formed in a U-shape andterminating in the connecting eyelet 19. The arm of the U adjacent theeyelet provides a finger grip which facilitates stretching the springwhen placing the eyelet over the anchoring screw 21, and obviates theneed for pliers or other attaching tool.

In FIG. 9 the supporting drum 4b is ungrooved, and a metal band with aV-groove 22bis disposed between a strip electrode 6a, like that of FIG.5 and the drum surface. The strip electrode is yieldingly held in thegroove 22b by the holddown 18 of FIGS. 1 to 5, or by those of FIGS. 6and 7. The grooved band 26 preferably is secured at each end by theeccentric screws 20.

In FIG. 10 the drum 4c is very shallowly grooved. Seated in its grooveis a composite band comprising' a metal ribbon 27 and a V-grooved ribbon28 of resilient foam material adhered to the metal ribbon. The stripelectrode 6a is positioned in the groove by the same holddown 18 ofFIGS. 1 to 10. 7

Shown in FIGS. 11 to 17 is a scanning assembly modified to hold anelectrode strip 36 in a non-helical curve around a drum 34. With anon-helical disposition the pressure spot of the strip electrode 36against the linear electrode 3 of FIG. 1 travels in non-linearrelationship to elapsed time. Such non-linear scanning is useful, forexample, in recording fathometers to compensate for non-linearpropagation rates of sound in water of different depths and densities.

The drum 34 of FIG. 11 is like the drum 4 of FIG. 1 in having a trulyhelical groove 42. Two eccentric screws 40 are located at the end of thegroove as shown and also at the end not shown. One register pin 41 isset in the groove, extending radially of the drum about the depth of thegroove.

A flexible 0.005 inch thick stainless steel band 37 (FIGS. 12 and 14)similar to ribbon 27 of FIG. 10 is adaped to fit snugly in the drumgroove. The band has keyholes 50 fitting over the eccentric screws 40,which are then turned to clamp the band to the drum. A register hole 51snugly receives the register pin 41 precisely to position the band 37lengthwise of the groove. Piercing the band are a series of slits 52which are curved relative to the linear edges of the band. When the bandis attached in helical shape to the drum the series of slits describes anon-helical curve around the drum. Ex-

tending in a curve parallel to the slits are a series of semi-circularspring fingers 53 struck upwardly at an angle of 45 to the band 37 andinclined toward the series of slits.

The modified strip electrode 36 (FIGS. 13 and 15) of 0.003 to 0.005 inchthick flexible stainless steel is folded with an upstanding panel 60inclined at an angle of approximately 45 to a series of integral basetabs 62. Extending in the same plane away from each base tab 62 is atongue 63 struck out of the strip. Intermediate the base tabs 62 aresemi-circular spring fingers 64 folded at approximately 45 to the planeof the base tabs and inclined away from the upstanding panel 60. Theendmost base tab 62 has a register hole 61 receiving the register pin41.

As shown in FIG. 17 the parts of FIGS. 11 to 16 are assembled by firstattaching the band 37 in the drum groove 42 as previously described. Thetongues 63 of the strip electrode 36 are then inserted in thecorresponding slits 52 of the band 37. The longitudinal edges of theslits may be struck up and down to facilitate entry of the tongues asshown in exagerated proportion in FIG. 17. The endmost base tab 62 withthe register hole 61 is fitted on the register pin 41. An elongate,rectangularly cross sectioned strip 38 of foam rubber or the like (FIG.16) is then compressed between the tabs 53 on the band 37 and theopposed tabs 64 on the electrode strip 36. Lateral compression of thefoam strip 38 between the tabs 53 and 64 forces sections of theupstanding electrode panel 60 against the opposed edges of the bandslits 52 thereby positively conforming the curvature of the upstandingpanel to the non-helical curve of the slit series. Also, because theinclined tabs -53 and 64 overlie the foam strip 38, vertical compressionof the foam'strip yieldingly urges the underlying base tabs 62 againstthe band 37. As previously similarly described with respect to FIGS. 1to 4, the spring holddown action of the foam strip allows flexing of theupstanding panel 60 and base tabs 62, and also both lateral andlongitudinal rocking of the strip electrode.

It should be understood that the present disclosure is for the purposeof illustration only and that this invention includes all modificationand equivalents falling within the scope of the appended claims. Thusthe strip electrode 6 need not be curved in a constant pitch helix, butmay vary in pitch. While a completely cylindrical drum is shown, anysupport extending on a cylindrical surface may be used.

We claim: 1. A scanning assembly for facsimile recording comprising acylindrical support, an elongate strip electrode folded lengthwise toform a .base seating on the support and a portion upstanding at anoblique angle to the base so that pressure on the upstanding portionflexes the base relative to the support, the electrode being curvedaround the support, e

a substantially elastic elongate spring holddown means extendingsubstantially the length of the strip and yieldingly bearing on the baseto urge the strip toward the support and allow the base to flex awayfrom the support, and

means for attaching the strip and holddown to the support.

2. A scanning assembly according to claim 1 wherein said holddowncomprises a coiled spring.

3. A scanning assembly according to claim 1 wherein said holddowncomprises a strand overlying the strip electrode and elastic meansbetween the strand and the support.

4. A scanning assembly according to claim 1 wherein said holddowncomprises anelastomeric strand.

5. A scanning assembly according to claim 1 wherein said strip electrodeis a longitudinally folded sheet and said holddown seats along the foldline of the sheet.

6. A scanning assembly according to claim 1 wherein said support has agroove curved therearound and said holddown yieldingly holds the stripelectrode in the groove.

7. A scanning assembly according to claim 6 wherein the strip electrodeis folded and the holddown positions at least one fold of the electrodein said groove.

8. A scanning assembly according to claim 1 wherein said groove isV-shaped to receive the fold of said strip electrode.

9. A scanning assembly according to claim 1 wherein said support hasconductive anchoring means at one end thereof, and an electricalconductor between said strip electrode and said anchoring means.

10. A scanning assembly according to claim 9 wherein said holddown isnon-conductive.

11. A scanning assembly according to claim 9 wherein said holddown isspring wire.

12. A scanning assembly according to claim 11 wherein said spring wirehas an eyelet formed at its end.

13. A scanning assembly according to claim 12 wherein said spring wirehas a U-form adjacent said eyelet.

14. A scanning assembly according to claim 12 wherein said cylindricalsupport has an eccentricheaded screw attached radially of the supportfor engagement by said eyelet.

15. A scanning assembly according to claim 1 wherein said holddowncomprises the sole means holding the strip on the support.

16. A scanning assembly according to claim 1 characterized by alongitudinally grooved band between said strip and support, the grooveof said band receiving said strip.

17. A scanning assembly according to claim 16 wherein said bandcomprises a strip of metal.

18. A scanning assembly according to claim 16 wherein said bandcomprises a ribbon of metal and a superimposed ribbon of resilientmaterial having a longitudinal groove therein.

19. A scanning assembly according to claim 1 wherein the holddown meanscomprises means disposed non-linearly around the support for engagingthe strip and holding it non-linearly curved.

20. A scanning assembly according to claim 19 wherein said stripengaging means comprises a linear band anchored on the support inhelical form and including strip positioning means extendingnon-linearly along the band.

21. A scanning assembly according to claim 20 wherein said positioningmeans comprises a series of longitudinal slits, said strip having acorresponding series of tongues engaging in the slits.

22. A scanning assembly according to claim 21 wherein said band andstrip have opposing portions adjacent said slits and tonguesrespectively positively positioning the strip on the non-linear curve ofthe slit series.

23. A scanning assembly according to claim 20 wherein said strippositioning means comprises a first series of fingers on the bandoverlying the strip.

24. A scanning assembly according to claim 23 wherein the strip has asecond series of fingers overlying the strip.

25. A scanning assembly according to claim 24 wherein the fingers of thefirst and second series are resilient.

26. A scanning assembly according to claim 24 characterized by anelastic strip engaged under the first and second series of fingers andyieldingly'bearing on the strip.

27. A scanning assembly according to claim 26 separably attached to thesupport.

29. A scanning assembly according to claim 19 wherein the strip engagingmeans is separably attached to the support.

30. A scanning assembly according to claim 1 wherein the holddownis'separably attached to the support. t

1. A scanning assembly for facsimile recording comprising a cylindricalsupport, an elongate strip electrode folded lengthwise to form a baseseating on the support and a portion upstanding at an oblique angle tothe base so that pressure on the upstanding portion flexes the baserelative to the support, the electrode being curved around the support,a substantially elastic elongate spring holddown means extendingsubstantially the length of the strip and yieldingly bearing on the baseto urge the strip toward the support and allow the base to flex awayfrom the support, and means for attaching the strip and holddown to thesupport.
 2. A scanning assembly according to claim 1 wherein saidholddown comprises a coiled spring.
 3. A scanning assembly according toclaim 1 wherein said holddown comprises a strand overlying the stripelectrode and elastic means between the strand and the support.
 4. Ascanning assembly according to claim 1 wherein said holddown comprisesan elastomeric strand.
 5. A scanning assembly according to claim 1wherein said strip electrode is a longitudinally folded sheet and saidholddown seats along the fold line of the sheet.
 6. A scanning assemblyaccording to claim 1 wherein said support has a groove curvedtherearound and said holddown yieldingly holds the strip electrode inthe groove.
 7. A scanning assembly according to claim 6 wherein thestrip electrode is folded and the holddown positions at least one foldof the electrode in said groove.
 8. A scanning assembly according toclaim 1 wherein said groove is V-shaped to receive the fold of saidstrip electrode.
 9. A scanning assembly according to claim 1 whereinsaid support has conductive anchoring means at one end thereof, and anelectrical conductor between said strip electrode and said anchoringmeans.
 10. A scanning assembly according to claim 9 wherein saidholddown is non-conductive.
 11. A scanning assembly according to claim 9wherein said holddown is spring wire.
 12. A scanning assembly accordingto claim 11 wherein said spring wire has an eyelet formed at its end.13. A scanning assembly according to claim 12 wherein said spring wirehas a U-form adjacent said eyelet.
 14. A scanning assembly according toclaim 12 wherein said cylindrical support has an eccentric-headed screwattached radially of the support for engagement by said eyelet.
 15. Ascanning assembly according to claim 1 wherein said holddown comprisesthe sole means holding the strip on the support.
 16. A scanning assemblyaccording to claim 1 characterized by a longitudinally grooved bandbetween said strip and support, the groove of said band receiving saidstrip.
 17. A scanning assembly according to claim 16 wherein said bandcomprises a strip of metal.
 18. A scanning assembly according to claim16 wherein said band comprises a ribbon of metal and a superimposedribbon of resilient material having a longitudinal groove therein.
 19. Ascanning assembly according to claim 1 wherein the holddown meanscomprises means disposed non-linearly around the support for engagingthe strip and holding it non-linearly curved.
 20. A scanning assemblyaccording to claim 19 wherein said strip engaging means comprises alinear band anchored on the support in helical form and including strippositioning means extending non-linearly along the band.
 21. A scanningassembly according to claim 20 wherein said positioning means comprisesa series of longitudinal slits, said strip having a corresponding seriesof tongues engaging in the slits.
 22. A scanning assembly according toclaim 21 wherein said band and strip have opposing portions adjacentsaid slits and tongues respectively positively positioning the strip onthe non-linear curve of the slit series.
 23. A scanning assemblyaccording to claim 20 wherein said strip positioning means comprises afirst series of fingers on the band overlying the strip.
 24. A scanningassembly according to claim 23 wherein the strip has a second series offingers overlying the strip.
 25. A scanning assembly according to claim24 wherein the fingers of the first and second series are resilient. 26.A scanning assembly according to claim 24 characterized by an elasticstrip engaged under the first and second series of fingers andyieldingly bearing on the strip.
 27. A scanning assembly according toclaim 26 wherein said support and elastic strip have interengagingregister means positioning the elastic strip longitudinally of the band.28. A scanning assembly according to claim 27 wherein the band,electrode strip and elastic strip are separably attached to the support.29. A scanning assembly according to claim 19 wherein the strip engagingmeans is separably attached to the support.
 30. A scanning assemblyaccording to claim 1 wherein the holddown is separably attached to thesupport.